OK, I've posted this code in some other topics aswell. I think it's very important everyone knows about this.

Most complex scripts fail running under IIS with relative paths or require 'file' files. Most of the time, a 'can't locate at @INC', or 'file not found' message appears. This is because the current directory in IIS is the WWW-root. I've seen a solution to this problem in the code of a different BB system.